I. Field
The present invention relates generally to communication, and more specifically to data transmission in a wireless communication system.
II. Background
A multiple-access system can concurrently support communication for multiple terminals on the forward and reverse links. The forward link (or downlink) refers to the communication link from the base stations to the terminals, and the reverse link (or uplink) refers to the communication link from the terminals to the base stations. Multiple terminals may simultaneously transmit data on the reverse link and/or receive data on the forward link. This may be achieved by multiplexing the data transmissions on each link to be orthogonal to one another in time, frequency, and/or code domain. The orthogonality ensures that the data transmission for each terminal does not interfere with the data transmissions for other terminals.
A multiple-access system typically has many cells, where the term “cell” can refer to a base station and/or its coverage area depending on the context in which the term is used. To increase capacity, the coverage area of each base station may be partitioned into multiple (e.g., three) sectors by using appropriate antenna patterns. Each sector is served by a base transceiver subsystem (BTS). The BTSs for all sectors of the same cell are typically located within the base station for that cell, and these sectors are considered to be co-located. In general, the term “sector” can refer to a BTS and/or its coverage area depending on the context in which the term is used.
In a sectorized system, the sectors of each cell typically utilize the same frequency band. Data transmissions in each sector of a given cell then represent potential interference to data transmissions in other sectors of the same cell. Isolation of interference among the multiple sectors of the same cell is normally achieved by controlling the antenna pattern for each sector such that the antenna gain drops quickly outside of the intended coverage area for the sector. However, the edge of each sector typically overlaps the edges of adjoining sectors. A terminal that is located on the boundary between two sectors of the same cell may then observe high “intra-cell” interference from a neighboring sector. This interference may substantially degrade performance.
There is therefore a need in the art for techniques to mitigate the deleterious effects of intra-cell interference for terminals located on the boundaries between sectors of the same cell.